Gulf of Alaska's salmon become scarce as ocean currents shift

A second straight year of weak king salmon returns around the rim of the Gulf of Alaska has state fisheries biologists wondering if they might be staring into the face of a bleak future.
Troubling discussions of PDO -- an acronym for something called the Pacific Decadal Oscillation -- have been spreading coast-wide as kings come back weak in river after river. Historically, there are indications that geographically widespread weakness like these are tied to a shift, or oscillation, in Pacific Ocean currents that causes cooler waters to pool in the Gulf of Alaska.